Unstacking mechanism



Jam 30, 1970 H E. TEMPLE 3,517,835

UNSTACKING MECHANISM Filed May 6. 1968 4 Sheets-Sheet 1 INVENTOR. I HIRAM E. TEMPLEE ATTORNEYS June 30, 1970 H. E. TEMPLE UNS'I'ACKING MECHANISM 4 Sheets-Sheet 2 Filed May 6, 1968 1NvNT0R. HIRAM E. TEMPLE FIG. 2

lza'unan, human 5' aliccullocf.

ATTORNEYS June 30, 1910 H.RE.TEMIIPLE 3,517,835

UNSTACKING MECHANI SM Filed May 6, 1968 4 Sheets-Sheet s v INVENTOR. WRAM EJTEMPLE mum, llama, & dl (cuuuch ATTORNEYS I June 30, Q (H. E. TEMPLE 351L335 UNS'I'ACKING MECHANISM Filed May 6, 1968 4 Sheets-Sheet 4 o 75 l3 5 3o 3To I I PLUNGER UP i I I I I \l |PLUNGER DOWN *1 IOSTRIP I I i- -ueo PUSH TRAY-- 1 I SUPPORT PADS IN i I I l SUPPORT PADS ou'r I I l i v DEM ND SWITCH INVENTOR. H!RAM E. TEMPLE BY 1 mm, lza'unan 5' a/h'cCulhi ATTORNEYS United States Patent O Yo k r Filed May 6, 1968, Ser. No. 726,680

- Int. Cl. B65g 59/04 U.S. Cl. 2148.5 12 Claims ABSTRACT OF THE DISCLOSURE Unstacking mechanism for removing plastic and/or metal trays from vertically indexed stacks of trays, presented in vertically stacked groups to an unstacklng station; a vertically moving lift plunger reciprocable downwardly to the stack and upwardly from the uppermost .tray in the stack to a raised position above the stack; a magnetizable lift cup having a lost motion connection with the plunger; a resilient suction cup on the plunger within the magnetizable cup, a motor driven, cam actuated arm swingable in a vertical plane to move the plunger upwardly and downwardly; motor driven cam actuated pivoted levers having support pads thereon, swingable inwardly and outwardly in timed relation wlth the movement of the arm to support an unstacked tray above the stack; stripper members above the pads for removing a tray raised by the plunger from the magnetizable cup or suction cup; and a transfer sweep member for moving the tray along the support pads to a takeaway conveyor.

One of the prime objects of the present invention is to design an unstacker which may be employed in a bakery, for instance, for handling trays which may be formed with an unbroken plastic bottom or with a metallic wire mesh bottom and which may be presented to the mechanism in vertical stacks which may include both the plastic trays and the steel mesh trays in random order.

Another object of the invention is to design highly reliable and efficient unstacking mechanism of the character described which is well suited to high speed operation adjacent a production line to automatically supply such trays individually to mechanism which loads packaged bread, for instance, on the trays.

Other objects and advantages of the invention will be pointed out specifically or will become apparent from the following description when it is considered in conjunction with the appended claims and the accompanying drawings, in which:

FIG. 1 is a side elevational view showing the mechanism in the process of raising a tray from a stack;

FIG. 2 is a left end elevational View thereof;

FIG. 3 is a top plan view thereof with certain parts broken away in the interest of clarity;

FIG. 4 is an enlarged, fragmentary, sectional elevational view illustrating the lifter cup assembly;

,FIG. 5 is a diagrammatic view indicating typical relative positions of the lift plunger and pan support pads during a cycle of movement;

FIG. 6 is a schematic representation of typical electrical control circuitry which may be employed.

Referring now more particularly to the accompanying drawings wherein a preferred embodiment of the invention only is shown, a letter F generally indicates the frame of my unstacking machine, which comprises a base 10, a pair of vertical left end support posts 11 and a pair of similar right end support posts 12 (FIG. 1), upper connecting side members 13 and upper connecting end members 14. Elevator mechanism generally designated 15 is 3,517,835 Patented June 30, 1970 provided on the frame F for lifting stacks S of nested, rectangular trays T to an unstacking mechanism generally designated 16 which operates to successively remove the uppermost tray from a tray stack S and deliver it to a discharge conveyor generally designated 17. The elevator mechanism 15 indexes to present the stacks of trays S to an unstacking station 18 and, when each of the trays T in the stack S has been lifted and discharged to the conveyor 17 during an elevator dwell period, indexes to present the next stack to the unstacking station 18.

THE ELEVATOR MECHANISM As FIGS. 1 and 2 indicate, the elevator mechanism 15 includes pairs of spaced apart chains 19 mounting spanning support bars 20' which are carried in spaced apart relation thereon, the bar 20 mounting tray support lugs 20a. The stacks S of trays T may be applied to the bars 20 manually or in a production bakery will be supplied by machinery automatically when the indexing chains 19 are in the dwell period. The chains 19 are supported by upper sprockets 21 fixed on upper support shafts 22, and lower sprockets 23 fixed to lower support shafts 24. As FIG. 1 indicates, the shafts 22 are journaled in bearings 25 supported by blocks 26 projecting from the channel members 11 and 12, and the lower shafts 24 are journaled in bearings 27 provided on blocks 28 which also project from the end members 11 and 12.

Provided to drive the elevator mechanism 15 is a gear head electric motor 29 having its output shaft 30 coupled, as at 31, to one of the shafts 24. A 'gear 32 fixed on the one shaft 24 is in'mesh with a gear 33 (FIG. 3) provided on a stub shaft 34 supported by a bearing 35 mounted on outboard support block 28 in FIG. 1 which, as FIG. 3 indicates, also mounts a sprocket 36 for driving the opposite shaft 24 through a connecting chain 37 trained also around a drive sprocket 38 on the opposite shaft 24.

THE UNSTACKING MECHANISM As FIG. 4 particularly indicates, the unstacking mechanism includes a vertically reciprocable plunger 39 on which a vertically yieldable support cup assembly generally designated 40 is provided. Mounted in fixed position on the lower end of plunged 39 is a resilient rubber suction cup 41, which may be of the type used on plumbers plungers, and, surrounding the cup 41, is a magnetizable cup 42 mounting a permanent magnet ring 43 of a type which is commercially available and maintains the cup 42 constantly magnetized. Both the cup 42 and ring 43 fixed thereto are freely slideable vertically on the plunger 39 for a purpose which will be later explained. The tubular plunger 39, which in FIG. 1 may be considered to be closed at its upper end, is mounted for reciprocating vertical movement in a slide bearing 44 supported on a cross rail 45.

An arm 46 pivotally supported as at 47 on a bracket 48 which spans the vertical end post 12 is bifurcated at one end, as shown at 49 in FIG. 3, to pass the upper end of the plunger 39. Provided in the upper end of the plunger 39 is a pin 50 which extends from both sides of the plunger 39 and is received in elongate slots 51 provided in the free end of arm 46. With this connection of plunger 39 to the arm 46, the arm 46 moves the post 39 upwardly and downwardly but the plunger 39 is able to move in a purely vertical path because the ends of pin 50 are capable of moving in the slots 51 to compensate for the arc traveled by the free end of the arm 46. The movement of arm 46 is controlled by a cam 52 which can extend up into a slot 53 provided in the arm 46 and is engaged by a follower roller 54 carried by the arm 46. As FIG. I particularly indicates, the cam 52 is fixed on a cam shaft 55 journaled in 3 bearings 56 provided on cross members 57 which span the vertical posts 11 and 12, as shown in FIG. 1.

A sprocket 58 (see FIG. 3) mounted on the shaft is driven via a chain 59 by a sprocket 60 mounted on a stub shaft 61 extending from a single revolution clutch 62 which is driven by a gear head motor 63.

Mounted in the path of a tray T being raised upwardly by the cup assembly 40 are a pair of stripper bars 64 connected with frame P which halt a tray T while the plunger 39 with its cup assembly 40 continues to move upwardly. To support the tray T when it has been stripped from the cup assembly 40, a pair of arms or lever frames 65 are provided which have elongate support pads 66 projecting inwardly at their lower ends (see FIG. 2). The arms 65 are pivotally supported, as at 67, from bracket members 68 mounted on the frame members 13 and normally are maintained in the swung in position in which they are shown in FIG. 2 by a spring 69 connected between cross brace members 70 which span the frames 65. The pairs of frames 65 are, however, movable laterally outwardly to the positions indicated at 65' in FIG. 2 by cams 71 mounted on the cam shaft 55. The cams 71 are engaged by follower rollers 72 mounted on blocks 73 which extend inwardly from the frames 65.

Mounted in position above the support pads 66 when they are swung to the in position shown in FIG. 2 is a transfer or sweep assembly generally designated 74 which is provided for moving a tray T from the support pads 66 over to the discharge conveyor 17 which may have powered rolls 17a. The sweep assembly 74 includes a pair of shafts 75 and 76 journaled in bearings 77 and 78 provided on frame cross members 79'. Provided on the shaft 75 are pairs of sprockets 79 and provided on the shaft 76 are a pair of sprockets 80 and, as shown in FIG. 3, the sprockets on shafts 75 and 76 are connected by endless chains 81. Tray engagingsweep members 82 depend from the chains 81 in position to engage a tray T supported by the pads or guides 66 and move it across to the discharge conveyor 17 when the sprockets 79 and 80 are revolved counterclockwisely in FIG. 1. The shaft 76 is driven by the gear head motor 63 via a chain 83 trained around a sprocket 84 (see FIGS. 2 and 3) provided on shaft 61 and a sprocket 85 fixed on shaft 76.

THE CONTROL SYSTEM Provided on the upper end of the plunger 39 is a switch actuator 86 adjustably mounted on a projecting block 87 and adapted to engage and actuate a normally open limit switch 88 provided in the circuit line x with motor 29, as shown in FIG. 6. The limit switch 88 is so positioned with respect to the actuator 86 that it is actuated only when the lift cup assembly 40 engages the bottom of the lowermost tray T of a stack S. When the switch 88 is closed, the motor 29 in circuit line x is energized and motor relay switches 29a and 2% are closed and opened, respectively. Motor 29 is driven to index the next bar 20 the required distance to present the next stack S of trays T to the unstacking station 18. Also provided in circuit line x in series with motor 29 is a normally closed switch 89 mounted on a bracket 90 depending from a horizontal brace member 91. A solenoid SOL for engaging the single revolution clutch 62 is connected in a circuit line y in series with the switch 29b and a demand switch calling for more pans to be delivered to the system on discharge conveyor 17. The motor 63 is in a circuit line z and is driven continuously. When the last tray has been removed, switch 29b is opened to deenergize the solenoid and the clutch 62 stops the plunger 39 in up position until the next stack of trays T is in position to be unstacked at station 18.

THE OPERATION In operation, it will be assumed that a new stack S of trays T has just been delivered to the unstacking station 18 and switch 89 has been actuated. At this time solenoid SOL is energized and shafts 55 and 76 are driven. At the beginning of the cycle the cams 52 and 71 maintain the plunger 39 in the up position and the support pads 66 in the in position to support the last tray T unstacked. Sweeps 82, however, which were stopped in the position shown in FIG. 1, move to the right in FIG. 1 to slide the tray T along the guides 66 and deliver it to the discharge conveyor 17. When the tray T clears the cup assembly 40, the plunger 39 commences to lower until the cup assembly 40 engages the uppermost tray T. If that tray is a solid plastic tray, suction cup 41 is deformed and the tray T is lifted by the cup 41 on the up stroke of plunger 39. When the tray T so lifted is moved past the supports 66, which in the meantime have been swung outwardly to the position indicated in chain lines at 65' in FIG. 2, it engages the stripper bars 64 and is removed from the suction cup 41. As this occurs, the cams 71 permit the support pads 66 to be drawn inwardly by spring 69' to form a platform on which the unstacked trays T may rest. The cycle is then repeated until all trays T in a stack S have been removed, whence switch 29a opens and stops the plunger 39 in the up position, the support pads 66 in the in position, and the sweeps 82 in the rear position shown in FIG. 1.

If the particular tray T being lifted were a steel wire mesh tray, it would be lifted by the magnitized cup 42, of course, rather than the suction cup 41. With the lost motion connection between the magnetized cup 42 and the plunger 39, the cup 42 with its permanent magnet 43 is free to be displaced upwardly on the plunger 39 when the uppermost tray T of a stack S is engaged and then is free to slide vertically downwardly on the plunger shaft 39 under the influence of gravity to engage the next uppermost tray T in the stack S. The rubber suction cup 41 also has a certain amount of vertical yieldability so long as the vertical height of stacks S remains within predetermined limits.

Of course, the upper end of tubular plunger 39 may be connected to a vacuum source such as a suction pump, and the stripping of the tray T could be accomplished by a valve which discommunicated the vacuum source when the plunger 39 had traveled upwardly far enough to dispose the tray T being lifted above the support pads 66.

It is to be understood that the drawings and descriptive matter are in all cases to be interpreted as merely illustrative of the principles of the invention, rather than as limting the same in any way, since it is contemplated that various changes may be made in the various elements to achieve like results without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. Unstacking mechanism for sequentially unstacking a stack 'of trays which may randomly be of different character comprising: means for supporting a plurality of vertically stacked trays; a lift assembly having a path of movement from a first position above said trays down to a lower position adjacent the uppermost tray; suction applying and magnetic force applying tray support means for said lift assembly arranged to facially engage an uppermost tray and lift it upwardly; said magnetic force applying tray support means comprising magnet material and being vertically yieldable when it engages said uppermost tray, relative to said suction applying tray support means; means for receiving the tray from one of said suction applying and magnetic force applying tray support means and moving it to a remote location; and means for moving the lift assembly between said positions.

2. The combination defined in claim 1 in which the suction applying tray support means comprises a resilient suction plunger cup which, when pressed against a tray and deformed, adheres to the tray.

3. The combination defined in claim 1 in which the means for moving the lift assembly comprises: cam means; motor means driving said cam means; and a pivotally mounted arm supported to pivot in a generally vertical plane and connected to said lift assembly; fo1 lower means on said arm riding on said cam.

4. The combination defined in claim 3 in which laterally movable tray support means are movable from a position out of the vertical path of a tray being lifted in to a position beneath said tray to support the tray in raised position; and second cam means driven by said motor means for movingthe laterally movable tray support members in timed relation with said arm.

5. The combination defined in claim 4 in which stripper means is supported in the vertical path of a tray being lifted to prevent the tray from being lifted beyond a predetermined location on the lift assembly; and said second cam means moves the laterally movable tray support means in under the tray to support it before it is released to fall.

6. The combination defined in claim 4 in which said laterally tray support means comprise a pair of generally vertically extending, pivotally mounted arm members having support pads on their lower ends.

7. The combination defined in claim 6 in which a transfer member has a path of movement along said pads to move a tray "from said pads to a location away from the stack.

8. The combination defined in claim 7 in which said transfer member comprises a sweep carried on endless chain means having a transfer run extending generally parallel with and above said pads.

9. Unstacking mechanism for sequentially unstacking a stack of trays which may randomly be of different character comprising: means for supporting a plurality of vertically stacked trays; a lift assembly having a path of movement from a first position above said trays down to a lower position adjacent the uppermost tray; first vertically yieldable, suction applying, tray support means normally fixed on said lift assembly in position to facially engage an uppermost tray and lift it upwardly; second vertically yieldable magnetic force applying tray support means for said lift assembly arranged to facially engage an uppermost tray and lift it upwardly; means for receiving the tray from one of said first and second tray support means and moving it to a remote location; and means for moving the lift assembly between said positions; said magnetic force applying tray support means having a lost motion connection with said lift assembly permitting said magnetic force applying tray support means to move upwardly relative to said suction applying tray support means when said magnetic force applying means engages the uppermost tray.

10. Unstacking mechanism asset forth in claim 9 wherein said magnetic force applying tray support means includes a magnetized cup; and said suction applying tray support means comprises a resilient suction cup provided inside said magnetized cup for handling non-magnetizable trays.

lift assembly includes vertically movable support means mounting said magnetic force applying and suction applying tray support means for movement from a raised position to a lowered tray engaging position; said magnetic force applying means normally extending below said suction applying tray support means and being vertically movable on said support means to a raised position to permit said suction applying tray support means to engage said uppermost tray after said magnetic force applying tray support means has engaged said uppermost tray.

12. The combination defined in claim 9, including tray support means movable from a position out of the vertical path of a tray being lifted in to a position beneath said tray to support the tray in the raised position.

References Cited UNITED STATES PATENTS 1,181,112 5/1916 Charebois 29464 2,217,983 10/1940 Hopkins 2148.5 X 3,087,722 4/1963 Neuberger 2148.5 X 3,191,746 6/1965 McBride 214- X 3,409,149 11/1968 Graux 2l4-8.5

GERALD M. FORLENZA, Primary Examiner G. E. ABRAHAM, Assistant Examiner US. Cl. X.R. 294-64, 65.5

11. The combination defined in claim 9 wherein said 

